Orfeo/Erismena, Hackney Empire, London

A white box containing stunted trees and a pile of white rocks, with a pitted moon in the background: Kathy Prendergast's set for Orfeo evokes a barren world into which the bewildered characters stumble, before Catherine Manley's bright-toned Muse lights the universe up with song. Orfeo regularly gets freight heaped on it - ENO's recent production set it amid dancing girls in Java - but director James Conway turns it into a tale of shamanism: plausibly, given that Orpheus cures ills, charms trees and rocks, and visits heaven and the underworld.

Conway has also chosen to replace the story's happy ending with Monteverdi's macabre alternative one, in which Orfeo dies as a blood-sacrifice. He has also superimposed an additional plot which is at times opaque, but that doesn't matter: this is one of the most truthful accounts of Monteverdi's great opera I've heard. With nine singers plus a large period band, English Touring Opera produce that madrigalesque sound that can only be achieved when everyone is a soloist in their own right.

As a foil to Manley's Euridice and Joana Thomé's plangent Messenger, Hal Cazalet's Orfeo is so expressive that he might almost be speaking his lines: his aria invoking echoes from violins, cornets and harp makes the whole earth stop and listen. Every bar of the choral sections radiates eagerness and ardour; the orchestra enchants.

The focus is where it should be, on the music: when something "happens" - as when Orfeo tenderly copulates with Euridice on their wedding day - the mind registers it as filtered through sound. If you don't know the world's first opera, catch this while you can.

The second work on this tour doesn't dwell on the same exalted plane, but affords pleasure of a different sort. Cavalli's Erismena was a hit in its day, but three centuries later its labyrinthine plot seems absurd. Conway and his cast wisely refuse to take it seriously, amplifying its sexual ambiguities to a hilarious degree. Comedians all, the singers manage to extract all the beauty latent in the score, with Laura Mitchell and Rachel Nicholls trading on the complementary colouring of their voices. Huw Rhys-Evans steals every scene he is in.

To Saturday (020-8510 4500), then touring ( www.englishtouringopera.org.uk)